Pilot Iroshizuku Kon-peki: Color, Bottle & Dry Time

A 50 ml Pilot Iroshizuku Kon-peki bottle drawn in proportion: heavy clear glass, black cap, deep cerulean ink and a conical recess in the base, beside a blue ink swab card; inset: the swab going from light wash to a deep pooled edge — The 50 ml Kon-peki bottle, drawn in proportion, with a swab of the ink.

Product facts

Product: Pilot Iroshizuku Kon-peki fountain pen ink, 50 ml bottle
Brand: Pilot
Brand origin: Japan
Made in: Japan^*
Material: Water-based dye ink in a glass bottle
Released: 2007^*
Price range: $$$$20–75 per item

Notes on these facts

Made by Pilot Corporation (Japan); sold in the US by Pilot Corporation of America. Made in Japan: Kohezi's listing for the 50 ml Kon-peki gives Made in: Japan and says Pilot has always made its own inks. Pilot's Japanese catalog page for INK-50-KO (read in full on October 20, 2026) doesn't state a country; its JAN, 4902505367281, carries Japan's 49 prefix, which shows where the code was registered, not where the ink was made. Source. Price: example listing. Released: Pilot's Japanese site says Iroshizuku went on sale in 2007 with five colors but doesn't name them, so 2007 is the line's launch year; we found no Pilot date for Kon-peki itself.
Price bands are typical US retail, checked October 2026. Conversions to US dollars are approximate, at October 2026 rates (US$1 = ¥158 = ₩1,330 = NT$32.5 = CN¥6.7 = SEK 9.9 = DKK 6.7 = ₺49.6 = C$1.41 = A$1.43; €1 = US$1.12; £1 = US$1.32; CHF 1 = US$1.21).

Key takeaways

The standard bottle holds 50 ml (1.7 fl oz); a 15 ml mini bottle is also sold.
Goulet's smear test puts Kon-peki's dry time at about 20 to 25 seconds.
Goulet rates its water resistance low: a wet page is barely legible.
Pilot's Japanese catalog lists the 50 ml bottle (INK-50-KO) as a water-based dye ink in a bottle of 82 × 86 × 36 mm weighing 271 g.
Pilot's Japanese site says Iroshizuku launched in 2007 with five colors (it doesn't name them); Kon-peki lists at ¥2,200 (about US$14) per 50 ml today.

What is Iroshizuku Kon-peki?

It’s a deep cerulean blue fountain pen ink in Pilot’s Iroshizuku line, sold in a heavy glass bottle. Kon-peki (紺碧) is usually translated as deep cerulean or deep azure blue, and Goulet sells it as Deep Cerulean Blue.

Pilot’s Japanese site says every Iroshizuku name comes from a Japanese landscape or season, and gives “a vivid sky clearing on a fine day” as the kind of scene a blue can carry. It says Pilot began planning Iroshizuku around 2002, when Japanese inks mostly came in black, blue, blue-black and red, and launched it in 2007 with five colors, adding five more the next year; the line now has 24. Pilot’s page doesn’t name the first five, so we can’t confirm Kon-peki was among them; the earliest Pilot mention we found is its November 2014 press release, which names Kon-peki as an example of the 24 colors.

Iroshizuku joins the Japanese words for color (iro) and droplet (shizuku). Kon-peki is one of the line’s best-known colors: Pilot put it in a “popular 3-color” mini set in 2014 and among the 12 colors chosen for cartridges in 2022. For a much darker blue in the same bottle, see Iroshizuku Tsuki-yo.

Kon-peki specs

Spec	Value
Maker	Pilot Corporation, Japan
Code	INK-50-KO (50 ml), JAN 4902505367281; Pilot USA item 69212
Bottle	50 ml (1.7 fl oz), glass; 15 ml mini also sold
Bottle size and weight	82 × 86 × 36 mm, 271 g, per Pilot Japan; 8.0 cm (3.1 in) tall, per JetPens
Bottle opening	19.3 mm (0.76 in), per Goulet
Ink type	Water-based dye (Pilot Japan catalog)
Launched	Line launched 2007 (Pilot Japan); Kon-peki’s own date not stated
Japan list price	¥2,200 (about US$14) per 50 ml, including tax
Water resistance	Low (Goulet)
Dry time	About 20–25 s (Goulet’s test)
Shading / sheen	Low / very little
Price band	$$$ ($20–75 per bottle)

JetPens’ figures come from another 50 ml Iroshizuku color, Ina-ho, in the same bottle. Pilot gives three bottle dimensions without saying which is the height, so our cover draws the bottle in proportion rather than to scale.

Kon-peki 50 ml and 15 ml bottles to scale, with fills per bottle: about 125 and 37 for a 0.4 ml Pilot CON-40, 62 and 18 for a 0.8 ml LAMY Z28, 28 and 8 for a 1.76 ml TWSBI ECO; dye-based, low water resistance, 20–25 s dry time — How many converter fills each bottle holds (bottle ÷ capacity), with Kon-peki's sourced properties.

How does Kon-peki write?

It writes wet and saturated, with an even color and little shading or sheen. Unsharpen says it runs on the wet side without leaking, and Pen Addict found the flow neither too dry nor too wet.

Goulet rates the shading low because the color stays fairly uniform; Pen Addict calls the shading subtle but lovely. Unsharpen saw very little sheen, with faint pink undertones only where the ink pooled.

How fast does it dry, and is it waterproof?

It dries in about 20 to 25 seconds in Goulet’s test, and it is not water resistant. Goulet notes it may still smear at 20 seconds from a wet-writing pen, and that a soaked page would be barely legible.

So don’t use it to address envelopes or sign documents. For that, a water-resistant ink such as Noodler’s Black is the better pick. For a lower-priced everyday blue, Waterman Serenity Blue costs less per bottle and is rated medium for water resistance by Mountain of Ink.

Which pens is it safe for?

Any fountain pen that takes bottled ink. Kon-peki is a plain dye ink, not a pigment, iron gall or shimmer ink, so it needs no special care.

Fill a converter such as the CON-40 in the Pilot Metropolitan, a LAMY Z28, or a piston filler from the bottle. At 0.4 ml per CON-40 fill, one 50 ml bottle is about 125 fills.

If you prefer cartridges, Pilot has sold Kon-peki as an Iroshizuku cartridge in Japan since May 16, 2022: six 0.9 ml cartridges for ¥990 (about US$6.30). JetPens sells them too. Those fit Pilot pens only.

How do you clean it out of a pen?

Flush with plain water until it runs clear. Dye inks like Kon-peki rinse out easily, which is one reason it’s a common first bottled ink.

Its wet flow means a little more ink stays in the feed, so give it an extra flush before you switch to a very different color.

What’s special about the bottle?

The heavy glass bottle has a conical recess in its base, so a nib or converter can reach the last of the ink. Retailers describe the glass as blown and the bottle as made to refill until the last drop.

Pilot’s Japanese catalog gives the 50 ml bottle as 82 × 86 × 36 mm and 271 g, JetPens lists it at 8.0 cm (3.1 in) tall and 293 g, and Goulet gives a 19.3 mm (0.76 in) opening. That is wide enough for most nibs, but large pens may need the bottle tilted as it empties.

Pilot adds that Iroshizuku’s packaging won a gold prize in the household goods category of the Japan Package Design Awards 2011.

Where is Iroshizuku Kon-peki made?

In Japan, according to a retailer listing. Kohezi gives Made in: Japan and says Pilot has always made its own inks. Pilot’s Japanese catalog page doesn’t state a country of manufacture.

Pilot’s Japanese site gives the launch year, 2007, and a list price of ¥2,200 (about US$14) including tax, or ¥2,000 (about US$12.70) before tax, for a 50 ml bottle in its September 2024 press release. The 15 ml Iroshizuku mini went on sale in Japan on November 25, 2014, per Pilot’s press release, and now lists at ¥1,100 (about US$7.00). Pilot added Iroshizuku cartridges in Japan in 2022, with Kon-peki among the colors.

Frequently asked questions

What color is Iroshizuku Kon-peki?

A bright, deep cerulean blue. Kon-peki (紺碧) is usually translated as deep cerulean or deep azure blue; Goulet sells it as Deep Cerulean Blue.

How big is a bottle of Iroshizuku Kon-peki?

The standard bottle holds 50 ml (1.7 fl oz) in heavy glass, and a 15 ml mini bottle is sold too. Pilot's Japanese catalog gives the 50 ml bottle as 82 × 86 × 36 mm and 271 g; JetPens lists it at 8.0 cm (3.1 in) tall.

Is Kon-peki waterproof?

No. Goulet rates its water resistance low and says a wet page would be barely legible, and Unsharpen also lists it as not waterproof.

Is Iroshizuku Kon-peki a pigment ink?

No. Pilot's Japanese catalog lists Iroshizuku as a water-based dye ink, and retailers agree. That's why it's easy to flush from a pen and also why it isn't water resistant.

How long does Kon-peki take to dry?

About 20 to 25 seconds in Goulet's smear test, and it may still smudge at 20 seconds from a wet-writing pen. Absorbent paper dries it faster; coated fountain pen paper slower.

Does Kon-peki shade or sheen?

Only a little. Goulet rates its shading low because the color is saturated and even, Pen Addict calls the shading subtle, and Unsharpen saw very little sheen.

What does the bottle's dent in the bottom do?

The Iroshizuku bottle has a conical recess in its base. Retailers say it lets a converter or nib reach the ink right down to the last drops.

Where is Iroshizuku ink made?

In Japan, according to a retailer listing (Kohezi: made in Japan), and Pilot is a Japanese company that makes its own inks. Pilot's Japanese catalog page doesn't state a country.

Sources (16)

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